1. Field of the Invention
The present invention relates to a device which is useful for both bridging and backing between metal studs in building construction.
2. Description of the Prior Art
In the construction of buildings the framework for the walls of a building is formed of horizontal sill members at the floor at the ends of which vertical corner posts support horizontal headers at the ceiling level above the sills. Between the corner posts there are upright supports, called studs, laterally spaced usually at uniform intervals to provide the necessary interior structural support for the wall.
Historically, the framework of a building wall was formed entirely of wooden members, including wooden studs. In recent years, however, the use of metal studs has gained increasing acceptance, especially in the construction of commercial buildings, such as office buildings and hospitals. It has been found that metal studs can be employed to advantage, since a suitable metal, such as galvanized steel, is stronger than wood, will not rot, is not subject to damage by pests, such as termites, and is economically feasible. The use of metal studs also avoids the depletion of hardwood forests. Furthermore, metal studs are now economically competitive with wooden studs in the building construction industry. Metal building studs are typically formed of ten to twenty gauge galvanized steel.
While wooden studs are formed of solid wood, typically having nominal cross section dimensions of two inches by four inches, the much greater structural strength of metal allows studs to be employed which are not solid, but rather have a channel shaped or "C-shaped" cross section. To conform to the architectural plans and building materials which have been developed over the years based on the use of wooden studs having specific cross sectional dimensions, commercially available metal studs are constructed with the same outer dimensions in which wooden studs have been manufactured for many years. Specifically, metal studs are typically formed of sheet metal bent to encompass a cross sectional area having nominal dimensions of two inches by four inches.
For ease of fabrication the metal studs are formed of sheet metal bent into a generally "U-shaped" cross section and in which a relatively broad central base is flanked by a pair of narrower sides that are bent at right angles to the base. The base typically has a uniform nominal width of either four inches or three and one half inches, and the sides of the U-shaped stud typically extend a nominal distance of two inches from the base. To enhance structural rigidity the edges of the sides of the metal stud are normally bent over into a plane parallel to and spaced from the plane of the base. These turned over edges of the sides thereby form marginal lips which are typically one quarter to one half an inch in width.
In building construction there are certain situations which require the building studs to be braced or linked transversely to provide enhanced structural rigidity. The studs must be transversely bridged when they are over eight feet in length so that they provide adequate stability in a lateral direction within the wall which they support. Also, certain situations require horizontal backing between studs in a building so as to provide structural support to resist forces acting normal to or parallel to the plane of the wall. For example, structural backing must be provided between adjacent studs within a wall against which a flight of stairs is built so as to provide the necessary structural stability for a handrail affixed to the wall. The requirements for structural stability and backing between adjacent studs are particularly stringent in hospitals and schools, the construction of which is closely regulated by governmental agencies. For example, in hospital construction a handrail secured to a wall must be able to resist an outward pull normal to the wall having a force of two hundred pounds, and a downward pull parallel to the plane of the wall having a force of two hundred pounds as well.
The provision of bridging and backing between wooden studs is relatively simple. Lumber is merely cut into short lengths to fit between the facing surfaces of the wooden studs. These short lengths are merely nailed in position. Boards that are cut to length from the same lumber stock used for stud construction may be inserted between adjacent studs with their broadest surfaces residing in a generally horizontal disposition to form bridging between adjacent studs. The same type of lumber may be cut into boards which are inserted between adjacent studs with their broadest faces residing in coplanar alignment with the edges of the studs facing the wall surface to be reinforced to provide backing between adjacent studs.
As previously noted, metal studs are not solid structures, but are essentially three sided hollow channels with relatively thin marginal lips turned over on the fourth, open side. The metal reinforcing material for use in forming bridging and backing is of the same construction. As a consequence, the metal sections of channel stock used for bridging and backing between adjacent metal studs have no end surfaces which can be fastened to the broad base portions of the upright studs.
In order to provide bridging and backing between metal studs it has been the practice to employ metal channels formed of essentially the same channel shaped stock as the metal studs by cutting that stock in lengths long enough to overlap the narrow sides of the studs facing the wall surface. Notches are cut out of the sides of the metal stock used to provide bridging and backing so that the base portions of the bridging and backing channels reside in direct contact with the sides of the metal studs facing the wall. Holes are drilled through the bases of the bridging and backing channels between the notched sides thereof and into the upright sides of the metal studs directly behind them. Metal screws are then used to fasten the notched bridging and backing channels to the narrow sides of the upright studs.
While the conventional technique for providing metal studs for bridging and backing does create structural stability, it also presents certain problems. Specifically, since the base portion of the notched channel stock passes over the sides of the studs facing the wall of the room, an outward protrusion into the room is created to the extent of the thickness of the base portion of the channel stock forming the bridging or backing. Furthermore, the heads of the screw which fasten the notched channel stock to the studs protrude outwardly beyond even the extra thickness of metal of the base portion of the channel stock. While the studs and cross connecting channel stock are all covered over with wallboard, nevertheless the extra thickness of the base portion of the cross connecting channel stock and the screwheads that fasten that channel stock to the studs causes the wallboard to protrude into the room at the locations where the studs are reinforced with bridging or backing. This inward protrusion detracts from the aesthetic appearance of the wall.
A further disadvantage of the existing technique for cross connecting metal studs is that the notched channel stock can only be mounted with the relatively broad base member of the cross connecting channel stock residing in a vertical plane adjacent the plane of only the adjacent sides of the studs against which the channel stock is positioned. Conventional cross connecting channel stock cannot be mounted in a generally horizontal disposition across the width of the metal stud in the manner of bridging between wooden studs, so as to provide structural rigidity across the entire width of the studs. That is, the conventional cross connecting notched channel members provide reinforcement only on the sides of the metal studs upon which they are mounted. Little reinforcement is provided for the opposite sides of the metal studs. As a consequence, notched metal cross connecting members must be mounted on both sides of the studs to achieve the structural reinforcement of bridging. This requires two metal cross members to achieve the stability provided by each wooden bridging cross connecting member conventionally used in cross connecting wooden studs.